With the development of the technology of communications, LTE-A (LTE-advanced), as an advanced system of LTE, may provide spectral bandwidth of up to 100 MHz, and support communications with a higher flexibility and quality, and at the same time, the LTE-A system has very good backward compatibility. In an LTE-A system, there is a plurality of component carriers (CC). One LTE terminal can only work over a certain backward compatible CC, while an LTE-A terminal with a stronger capability may perform transmission simultaneously over multiple CCs, i.e. an LTE-A terminal transmits and receives data simultaneously over a plurality of component carriers, thereby achieving the purpose of improving bandwidth. The technology is referred to as multi-carrier aggregation technology.
With the progress of standardization, some companies propose new carrier types, endowing these carriers with new characteristics, but these do not reach an agreement. These carrier characteristics are summarized below. New carrier types mainly comprise carrier segment and extension carrier.
The carrier segment is a non-compatible carrier (referring to not providing compatibility with regard to previous versions), and the carrier segment cannot be used alone, but can only be used as a part of bandwidth of a certain backward compatible carrier, so as to increase the transmission capability of a data domain of the backward compatible carrier. The sum of bandwidth of the carrier segment and a paired backward compatible carrier is not greater than 110 resource blocks (RBs for short), and the extension carrier is a non-independently operated non-backward compatible carrier, which must be used in pair with a certain backward compatible carrier. The relevant characteristics of the extension carrier and the carrier segment are as shown below.
The characteristics of the non-compatible carrier are different from the previous R8 standard. The first 3 orthogonal frequency division multiplexing (OFDM) symbols of a subframe of R8 are used for transmitting a physical downlink control channel (PDCCH), and the remaining OFDM symbols are used for transmitting a physical downlink shared channel (PDSCH), while all the OFDM symbols included m a subframe of the current non-compatible carrier are used for transmitting the PDSCH, and the position where a cell-specific reference signal (CRS) occupies a resource element (RE for short) is also used for transmitting data information.
Statistics show that 80%-90% of system throughput in the future will occur in indoor and hotspot scenarios. As a technology which significantly increases system throughput and improves the overall network efficiency, heterogeneous networks may well satisfy the requirements proposed by LTE Advance. The heterogeneous network architecture introduces some transmission nodes with lower transmission power with respect to conventional cell base stations, comprising a picocell, femtocells and a relay used for signal relay. The introduction of these nodes may well guarantee the coverage of indoor and hotspot scenarios; the transmission power of these nodes is low, which is convenient to flexibly deploy networks; and at the same time, the coverage area of these nodes is small, which may be more convenient to use potential high frequency band spectrum of LTE Advanced. However, the introduction of new nodes change the original network topology structure, which makes inter-cell interference in such network structure become a new challenge.
In heterogeneous networks, in order to guarantee backward compatibility, the CRS is sent in each subframe. Therefore, even if in an almost blank subframe (ABS), the CRS of an aggressor cell (sector) is to be sent, while the CRS of the aggressor cell will result in significant interference for a victim (weak) UE of a neighbouring cell. In LTE common-frequency networking, the aggressor cell and the victim cell may avoid mutual conflicts of CRSs between cells by configuring different physical cell ID (PCI for short). However, the CRS of the aggressor cell may also interfere an RE corresponding to the victim UE of the neighbouring cell, which RE may be an RE of a control domain, and may also be an RE of a data domain.
When a receiver demodulates and decodes, if some unreliable data information is received, obvious mis-judgement for demodulation and decoding will be caused, making the receiver performance reduce significantly. A certain RE which is strongly interfered by the CRS of the aggressor cell is unreliable data information, and the existence of these REs which are strongly interfered makes the performance of the control domain and the data domain decrease.
In the case where the control domain RE is strongly interfered by the CRS of the aggressor cell, since the RE resources occupied by control signalling are few, if some certain REs are strongly interfered by the CRS of the aggressor cell, information about the victim UE control domain may not be received reliably, and in particular, the decoding of the physical downlink control channel may fail. In addition, knocking off the RE bearing information will increase the effective encoding rate. If only the RE which is interfered in the control domain is directly knocked off and rate matching is simply used, the performance of the control channel may also not satisfy the requirements of normal communication. The control domain comprises important system information and control information guaranteeing correct data channel decoding, and is the primary condition of normal communication of the system; therefore, guaranteeing the reliable receiving of the control domain is of great importance.
Since the special time slot of a time division-synchronous code division multiple access (TD-SCDMA) system is a fixed configuration, while the special subframe of a TD-LTE system may be flexibly selected as required, the configuration of the special subframe of TD-LTE should be reasonably selected according to service time slot configurations of the two systems and the special time slot situation of TD-SCDMA, trying to realize no mutual interference between the two systems only if the service time slots and special time slots of the two systems are synchronized. With reference to “TS36.211 Evolved Universal Terrestrial Radio Access (E-UTRA), Physical Channel sand Modulation”, the standard situations of LTE-TDD special subframes are specifically as shown in Table 1 below, and Table 1 indicates the numbers of OFDM symbols occupied by a downlink pilot time slot (DwPTS), a guard period (GP) and an uplink pilot time slot (UpPTS) in different configurations.
TABLE 1Configurations of special subframes in LTE TDD (length ofDwPTS/GP/UpPTS)SpecialsubframeConventional CPExtension CPconfigurationDwPTSGPUpPTSDwPTSGPUpPTS0310138119483210392311210 14121372539282693917102———8111———
When TD-SCDMA 2:4 is configured with TD-LTE 1:3, according to an existing LTE (LTE-A) configuration method, in order to realize synchronization between two systems so as to reduce interference, LTE TDD may only use configuration 0 and configuration 5 in Table 1, and at this moment, the DWPTSs both only need to occupy 3 symbols without a symbol bearing a service signal. In such configuration, the DWPTS cannot transmit a service, and at this moment, it is a 2:2 configuration situation with respect to upload/download (UL/DL); although 1 downlink service subframe data symbol is added when UL/DL is 1:3, due to the proportion limit of special subframes, the DWPTS reduces multiple symbols which may be used for data transmission; therefore, the peak/average throughput has a relatively large loss, and the overall efficiency is relatively low.
Therefore; the DwPTS, GP and UpPTS in special subframes are re-configured. The typical value of the number of OFDM symbols in the DwPTS is set as 5 or 6, wherein 3 OFDM symbols are used for transmission control, and the remaining OFDM symbols are used for transmitting a service; therefore, the loss of peak/average throughput is effectively improved, and the overall efficiency is significantly increased.
In the prior art, the TB size is determined according to a physical resource block allocation number NPRB together with a transmission block size index ITBS. Since the number of resources which may transmit data of physical resource blocks in the scenario mentioned above changes, if the original transmission block definition method is still used, the spectrum efficiency in the scenario mentioned above will decrease. Hence, a new method for determining the size of transmission blocks needs to be considered, so as to improve the spectrum efficiency in the scenario mentioned above.
In the prior art, when a TB block is in a one-layer space multiplexing condition, the conversion relationships between the TB size and the physical resource block allocation number NPRB and the transmission block size index ITBS are as shown in Table 2 below:
TABLE 2Size of TB block when system bandwidth is 10 PRBs in one-layer space multiplexingNPRBITBS123456789100163256881201521762082242561245688144176208224256328344232721441762082562963283764243401041762082563283924405045684561202082563284084885526326965721442243284245046006807768726328176256392504600712808936103271042243284725847128409681096122481202563925366808089681096125613849136296456616776936109612561416154410144328504680872103212241384154417361117637658477610001192138416081800202412208440680904112813521608180020242280